Paul,

I'm not an engineer but you and others on the newsletter list might
find an article in this month's Sport Aviation worth reading. It
deals with a newer approach to detecting defects through vibration
analysis. It could be useful for the TTC project since so much of
what you are using are 'one-off' pieces.

The EAA article can be found here:

https://www.eaa.org/en/eaa/eaa-news-and-aviation-news/2015-news/12-10-2015-breakthrough-technology-of-advanced-vector-analytics-promises-safety-reliability-savings


The company it covers is a Latvian startup called Advanced Vector
Analysis (AVA) and their approach is apparently so effective it
reduces the number of sensors required significantly. They measure
the normal x-, y- and z- axes but add a fourth dimension, i.ie.
tracking vibration over time. I'm assuming you can track down the
academic research publications documenting the processes and results.
The AVA website can be found here: http://www.ava-labs.com/en/

Regards,

Jack Hilditch

Paul, as an acoustics/vibration engineer I have to sound either an alarm
or a "who cares?" about this one. The key from the article is that they
have already burned through $3M in government grants and "pre-seed"
money. Airframe and engine makers have been recording and analyzing
3-axis vibration over time for decades and it is very effective if
coupled with an understanding of the structures analysis that come out
of the data you get. Modern finite element analysis helps to resolve
some of the issues that come up, but you still need a lot of sensors
because you can't know the compliance (stiffness) of structure between
some point and some other point unless you measure it, which takes
measurements at both points and some places in between. It might be good
work but not likely to be revolutionary.

The TTC engine is a good case in point. The current crop of propeller
analysers for 1/10 of what they cost 20 years ago is pretty good at
solving issues that would come up. To make sense of how it was working
in the engine mount you'd need strain gages at several locations, no way
around it. Even gradient strain gages only tell you so much. There is
lot to be done but people already working in this field have shown that
there are really no surprises as the field develops to capitalize on
evolution in computer systems.

David Josephson

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